Strange Quarks in the Proton and Quark-Hadron Duality

Dr. Tony Forest
Louisiana Tech University
Department of Physics

Our understanding of the proton and neutron as a system of up and down quarks has undergone substantial modification over the last few decades.   One of the first indications that this was an incomplete description of the nucleon occurred over 20 years ago when the European Muon Collaboration reported that strange quarks have a nonzero contribution to the net spin of the proton.  A natural question from this observation would be to ask if strange quarks also contribute to the magnetic moment of a nucleon.  I will present the results from several parity violation experiments designed to measure this contribution.  The current theoretical description of this complicated nucleon system has been divided into two camps.  One description uses quarks and gluons as the degrees of freedom for the system while another uses hadrons.  Recent experiments have revealed a dualistic property of the nucleon in which the low energy behavior of a nucleon is on average the same as a nucleon's response at high energies.  The implications of this Quark-Hadron Duality on future experiments at Jefferson Lab will discussed.